It seems the power band comes and goes pretty quickly with the 6spd. I don't pull much but do mostly highway driving. What do you think about going to 3.55s? I have some 315s I am going to add buy I don't think they will make a grave difference. I think a longer power band would be more beneficial. Your thoughts?

 

How are you going to fit 315's on a 2wd?

 

If you already have 3.73's, the 315/70 tires will be about the same as going to 3.55 gears with the stock 265/70 tires.

If I remember right, the 315/70 w 3.73 rear ratio will work out an effective 3.40 rear ratio.

I'm under 2k RPM now at >75 MPH with my 3.73's and 315's.
Kris

 

turboost,

I have 315's and the 3.73 gears. I would not want any higher gearing than this. Any taller and I think you'll notice a loss in performance. You can't just keep going higher and higher on the ratios and expect decent performance or higher and higher mileage.
By longer powerband I assume you mean a higher speed in each gear. Yes, you will get that (except maybe in OD and locked up), and assuming you ran it to redline in each gear, (how silly), but the acceleration will be less and the mileage will be less with the 315's. If it's pulling power you want, stay with the lower gears. If it's mileage you want, stay away from the 315's and /or slow down. It seems to be vehicle speed and rolling resistance, not gearing, that affects mileage.

Wetspirit

 

I understand that the tires are not going to help mileage due to the added weight. By longer power band I mean all the gears last longer. Instead of having to shift out of 3rd at 40mph (hypothetically) I can take it safely to 45mph. I know this isn't ideal for pulling but I don't pull much very often. I think this would make each gear more usable for city and highway driving.

 

turbo, I didn't see what gears you currently are running, but the difference between 3.73's and 3.54 is pretty small (around 5%). That translates you running up to 42 instead of 40. Or 73 instead of 70. big deal.

I don't think the cost of changing gears would ever be paid for by improved fuel economy over the trucks life of ownership. I'd invest the cash somewhere else - maybe a box and an exhaust.

 

I am running 285s on my truck and if I remember correctly that equates to about a 3.54 ratio. I am not sure if there is much of a weight difference between the stock and 285s but the stock tires had more of a highway tread and a higher inflation rating so I would probably get better mileage with the stock tires. I put the 285s on at around 600 miles so I can't make a mileage comparison.

I don't think there is enough difference between a 3.55 ratio and a 3.73 ration to make much of a difference in mileage or the power band.

 

I don't think the 285's would drop the ratio that low...

Doesn't the math make 285's run 3.61 and 315's run 3.43?

 

My stock tires were 31.4" tall and the new tires are 32.8". That is a difference of about 4.3% so that would make the new ratio about 3.57. I just used percentages to calculate the difference but there is probably a more accurate way to do the math.

 

I compared the actual rev per mile from the manufacter's data sheets...but we ar talking such small differences anyways...just being a pain in the butt!